We report one infant, who in the course of therapy of bacterial urinary tract infection developed fungal UTI and acute kidney injury. It was caused by coexistence of well-known risk factors and additionally intestino-vesical fistula. Appropriate and timely introduced treatment with intravenous fluconazole proved to be therapeutic in the patient. Our report shows that in every case detailed analysis of predisposing factors should be performed and appropriate diagnostic studies ordered, including the possible presence of other - less common - factors, e.g. defects in the gastrointestinal tract.